Charge forming apparatus



June 7, 1966 B. c. PHILLIPS CHARGE FORMI NG APPARATUS Original FiledNov. 27, 1959 6 Sheets-Sheet 1 June 7, 1966 B. c. PHILLIPS 3,254,880

CHARGE FORMING APPARATUS i liu nlull lik 60a. INVENTOR: 45 55 77 6h 5BERNARD [7.PH1LLJP5.

fIE-1Z- BY ATTO R N EY June 7, 1966 B. C. PHILLIPS CHARGE FORMINGAPPARATUS Original Filed NOV. 27, 1959 6 Sheets-Sheet 5 Ital INVENTOR:17 b jib .BERNAHD LZFHILLJPS.

BY I15 CLE- ATTORNEY June 7, 1966 B. c. PHILLIPS CHARGE FORMINGAPPARATUS 6 Sheets-Sheet 4 Original Filed Nov. 27, 1959 INVENTOR IBERNARD .6. PHILLIPS.

ATTORN EY m-Z i- June 7, 1966 B. c. PHILLIPS CHARGE FORMING APPARATUS 6Sheets-Sheet 5 Original Filed Nov. 27, 1959 V a m 444 0 EL Y Quiz mm M 2a W m 4 M 7 J ANY 0/ d 5. NB 2i H. IMW/ M H 5 A B 6 4% w. a 2 w, J d aad 8 5 d 0 6 d d B 5 5 k2 m m 11 1 m 5 Khalid L =i-l v.

June 7, 1966 B. c. PHILLIPS CHARGE FORMING ACIIIPARATUS 6 Sheets-Sheet 6Original Filed Nov. 27, 1959 INVENTOR BERNARD EPHILLIPS.

ATTORNEY United States Patent 3,254,880 CHARGE FORMING APPARATUS BernardC. Phillips, Toledo, Ohio, assignor to The Tillotson ManufacturingCompany, Toledo, Ohio, a corporation of Ohio Continuation of applicationSer. No. 855,688, Nov. 27, 1959. This application July 15, 1963, Ser.No. 295,123

' 6 Claims. (Cl. 261-41) This is a continuation of my application SerialNo. 855,688, filed November 27, 1959, now abandoned.

This invention relates to charge forming apparatus or carburetor for usewith internal combustion engines and more especially to charge formingapparatus of the diaphragm type especially adapted for deliveringcombustible mixture to internal combustion engines which are adapted foruse in various angular positions.

Internal combustion engines, and especially those of comparatively smallhorsepower, are used extensively for powering chain saws, lawnmowers,small boats and similar uses where the engine and charge formingapparatus are sometimes tilted to extreme angular positions, and enginesused for powering lawnmowers sometimes traverse rough terrain causingsubstantial vibration of the engine and charge forming apparatus.

The conventional type of charge forming apparatus or carburetorembodying a float-actuated fuel inlet control valve is unsatisfactoryfor use with engines which are operated in substantial angular positionsor subjected to excessive vibration. Charge forming devices embodyingdiaphragm controlled fuel inlet valve means have been used and haveovercome some of the disadvantages of float-controlled devices;

The present invention embraces a charge forming apparatus of thediaphragm type in which the components and fuel channels or passages arearranged in a compact manner whereby the charge forming apparatus may bemanufactured in substantial quantities and at'low cost.

Another object of the invention is provision of a diaphr-agm typecarburetor embodying an improved lever and valve arrangement forcontrolling fuel flow from a supply into the carburetor which is ofcompact construction elfecting a substantial reduction in the weight ofthe carburetor.

Another object of the invention is .the provision of a diaphragm typecarburetor provided with a shallow fuel chamber or passage disposedclose to the air and fuel mixing passage facilitating the transfer ordelivery of fuel from the inlet to the mixing passage with a minimum oflift or differential pressure in the mixing passage and in which thedelivery of the fuel into the mixing passage is controlled by engineaspiration.

Another object of the invention is the provision of a carburetor orcharge forming apparatus capable of providing for modification of thefuel channels or metering system and adjustments in order to facilitatea wide scope of calibration to adapt the carburetor to various types andsizes of engine and operating conditions, the carburetor embodying ameter-ing arrangement adaptable to operating conditions of two or fourcycle engines of the single cylinder or multi-cylinder type.

A further object of the invention is the provision of a diaphragm typeof carburetor embodying a diaphragm actuated lever construction and fuelinlet control valve arrangement fostering improved stability of fuelflow control and which does not vibrate appreciably under adverseoperating conditions such as movement of the engine and carburetorencountered with a power driven lawnmower and thereby obtain better fueleconomy.

A further object of the invention is the provision of carburetorembodying a diaphragm-actuated fuel flow amass Patented June 7, 1965 icecontrol means facilitating the placement of the fuel inlet on a side ofthe carburetor and wherein the diaphragm is instantly responsive tominute variations in pressure in a mixing passage .whereby the fuelrequirements of the engine are satisfied at all engine speeds.

Still another object of the invention resides in a carburetoi'. of thediaphragm type wherein fuel is delivered into a mixing passage under theinfluence of engine aspiration and operable with a minimum of lift ordifferential pressure.

Still a further object of the invent-ion is the provision of a diaphragmtype carburetor embodying a fuel flow control system, including a leverof the second order of levers providing a compact construction which ishighly sensitive to minute pressure variations in the mixing passage andyet effects a stable control of the fuel fiow under adverse operationconditions.

Further objects and advantages are within the scope of this inventionsuch as relate to the arrangement, op-

eration and function of the related elements of the struc- FIGURE 1 is a'side elevational view illustrating the form of charge forming apparatusor carburetor of the invention; I

FIGURE 2 is a top plan view of the charge forming device or carburetorshown in FIGURE 1;

FIGURE 3 is an enlarged longitudinal sectional view taken substantiallyon the line 3-3 of FIGURE 2;

FIGURE 4 is an enlarged transverse sectional view taken substantially onthe line 44 of FIGURE 2;

FIGURE 5 is a sectional view taken substantially on the line 5-5 ofFIGURE 1;

FIGURE 6 is a transverse sectional view taken substantially on the line66 of FIGURE 2;

FIGURE 7 is a transverse sectional view taken substantially on the line77 of FIGURE 1;

FIGURE 8 is a side elevational view illustrating a modified form ofcarburetor of the invention;

FIGURE 9 is an enlarged longitudinal sectional view of the carburetorshown in FIGURE 8;

FIGURE 10 is a transverse sectional view taken substantially on the line.1010 of FIGURE 8;

FIGURE 11 is a transverse sectional view taken stantially on the line1111 of FIGURE 8;

FIGURE 12 is an enlarge-d transversed sectional view taken substantiallyon the line 12-12 of FIGURE 9;

FIGURE 13 is a sectional view taken substantially on the line 1313 ofFIGURE 8;

FIGURE 14 is a side elevational view illustrating an other form ofcarburetor of the invention;

sub-

FIGURE 15 is an enlarged longitudinal sectional View through thecarburetor illustrated in FIGURE 14;

FIGURE 16 is a transverse sectional view taken substantially on the line1616 of FIGURE 14;

FIGURE 17 is a transverse sectional view taken substantially on the line17--17 of FIGURE 14;

FIGURE 18 is an enlarged transverse sectional sectional view'takensubstantially on the line 18-18 of FIGURE 15;

FIGURE 19 is a sectional view taken substantially on the line 19-19 ofFIGURE 14;

FIGURE 20 is an elevational view illustrating modified form ofcarburetor of the invention;

FIGURE 21 is an enlarged longitudinal sectional view through thecarburetor construction of FIGURE 20;

FIGURE 22 is a transverse sectional view taken substantially on the line22-22 of FIGURE FIGURE 23 is a transverse sectional view takensubstantially on the line 2323 of FIGURE 20;

FIGURE 24 is an enlarged transverse sectional view taken substantiallyon the line 24-24 of FIGURE 21;

FIGURE 25 is a sectional view taken substantially on the line 2525 ofFIGURE 20;

FIGURE 26 is a side elevational view of another form of carburetor ofthe invention;

IGURE 27 is an enlarged longitudinal sectional view of the carburetorshown in FIGURE 26;

FIGURE 28 is a transverse sectional view taken sub stantially on theline 2828 of FIGURE 26;

FIGURE 29 is a transverse sectional view taken substantially on the line2929 of FIGURE 26;

FIGURE 30 is an enlarged transverse sectional view taken substantiallyon the line 30-30 of FIGURE 27;

FIGURE 31 is a sectional view taken substantially on the line 3131 ofFIGURE 26;

FIGURE 32 is a transverse sectional view showing a modified form offloat control lever and spring arrangement of the invention, and

FIGURE 33 is a sectional view illustrating a modified form of fuel inletvalve and lever control mechanism.

While the charge forming apparatus or carburetor of the presentinvention illustrated in the drawings is particularly adapted forsupplying fuel and air mixture to internal combustion engines of the twocycle type, it is to be understood that the charge forming apparatus ofthe invention may be utilized with other types of internal combustionengine such as those of the four cycle type or Wherever a diaphragm typecarburetor or charge forming apparatus may be found to have utility.

It should be noted that in all forms of the carburetor or charge formingapparatus of the invention disclosed that the lever construction fortransmitting or transferring movement of the diaphragm to a valve forcontrolling the fuel inlet of the carburetor is of the second order oflevers wherein the fulcrum of the lever is disposed at one end thereofand is preferably of a right angle configuration or shape providing acompact diaphragm, lever and inlet valve construction which is highlysensitive to minute pressure variations in the mixing passage yetproviding for improved stability and immunity from vibration such aswould adversely affect the fuel economy.

In all forms of the invention disclosed the fuel transfer or diaphragmchamber in the carburetor body is shallow and is disposed close to themixing passage whereby a minimum lift is afforded for the aspiration offuel from the diaphragm chamber into the mixing passage. The smallamount of fuel in the diaphragm chamber has a minimum effect upon thediaphragm position whereby the diaphragm is instantly responsive tominute variations in pressure in the mixing passage.

Referring to the drawings in detail, and initially to the charge formingapparatus or carburetor shown in FIGURES 1 through 7, the carburetor isinclusive of a body or body member 10 which may be fashioned of die castmetal or of suitable molded resin of a character which is not subject toimpairment tor deterioration by hydrocarbon fuels. The body 10 is formedwith a longitudinally extending air and fuel mixing passage 12, themixing passage including a Venturi construction 14 the choke band orzone of maximum restriction being indicated at 15, an air inlet region16 and an outlet region 18.

Extending across the air inlet region 16 is a shaft 20 supporting adisk-type choke valve 21 secured to the shaft by a screw 22, the shaftbeing journaled in hollow bosses formed on the body as shown in FIGURE2. The shaft 20 is provided with a manipulating arm 24 for regulatingthe position of the choke valve which is employed in starting the enginewith which the carburetor is used.

The carburetor body 10 is provided with bosses 26 bored to journallysupport a shaft 28 extending across the outlet region of the mixingpassage and mounting a disk valve 30 held in place by means of a screw31 which forms a throttle valve for controlling the flow of fuel and airmixture through the outlet. The shaft 28 is provided with a manipulatingarm 32 for operating the throttle valve 30.

The outlet end of the carburetor body 10 is formed with a mountingflange 34 for connection with a crankcase of a two cycle engine or whichmay be connected with the manifold of a four cycle engine, the mountingflange having openings 35 to receive securing bolts (not shown). The airinlet end 16 of the body 10 may, if desired, be provided with an airfilter or an air cleaner for screening the air entering the mixingpassage.

The body 10 of the carburetor is formed with a shallow fuel chamber orfuel transfer passage 38. A flexible member, membrane or diaphragm 40extends across and forms one wall of the chamber 38 as particularlyshown in FIGURES 3 and 4.

It should be noted that the shallow fuel chamber or passage 38 is placedor disposed as close as possible to the mixing passage 12 in order toreduce the lift to facilitate delivery of the liquid fuel into themixing passage as ereinafter explained. The diaphragm 40 is preferablyformed of a flexible textile material such as Nylon cloth impregnatedwith a resin or synthetic rubber or oher coating to render the diaphragmimpervious.

The diaphragm 40 in the embodiment illustrated is substantiallycircular. Disposed between the peripheral region of the diaphragm 40 anda flat or planar surface of. the carburetor body 10 is an annular gasket42 to effect a seal between the periphery of the diaphragm and thecarburetor body. A plurality of projections 43, one

of which is shown in FIGURE 3, project through suitable openings formedin the peripheral region of the diaphragm 49, the peripheral region of acover plate 44 and the gasket 42 to properly position the gasket,diaphragm and cover plate with respect to the carburetor body 10.

The cover plate 44, preferably formed of sheet metal and of circularcontour, is secured to the body 10 by screws 45. The central region ofthe cover plate 44 is recessed away from the diaphragm to provide achamber 46 to accommodate flexure or movement of the diaphragm, thechamber 46 being vented to the atmosphere by means of a vent or opening47 to equalize the pressure in the chamber 46 irrespective of therelative position of the diaphragm 43.

The diaphragm 40 is fashioned to facilitate relative flexure or movementwithout stretching the material of the diaphragm. The diaphragm is madeof very thin highly flexible material to render it sensitive to minutevariations or changes in pressure in the fuel chamber 33 to facilitateefficient and uniform delivery of liquid fuel to the mixing passageunder aspiration or subatmospheric pressure set up or established in themixing passage by engine operation.

Means is provided in the carburetor for regulating or controlling theflow of fuel from a supply into the diaphragm chamber or fuel transferpassage 38. It is to be understood that any suitable fuel supply may beutilized such as a fuel tank located to flow fuel by gravity to thecarburetor or, if desired a suitable pump may be employed for conveyingfuel to the carburetor. As shown in FIG URE 4, the body 18 is fashionedwith a hollow boss portion 50 threaded as at 51 to receive a threadedportion of an inlet fitting 53 provided with a shank portion adapted toaccommodate a flexible supply hose or other tubular means, the fitting53 being formed with a fuel inlet passage 54.

Also disposed in the bore in the boss 50 is a hollow sleeve, fitting orvalve cage 56 which accommodates a valve body 58 slidably disposed inthe sleeve. The valve body 58 is of polygonal cross-section tofacilitate flow;

of fuel along the valve body, one end of the body being formed with aconically-shaped valve portion 60.

The fitting 56 is formed with a recess accommodating an annular valveseat 62 which is preferably formed of scmihard synthetic rubber or othermaterial which is resistant to deterioration to hydrocarbon fuels, theend of the inlet fitting 53 securing the sleeve 56 and valve seat 62 inplace.

The cone shaped valve 60 extends into and cooperates with the seat 62for regulating fuel flow controlled by the relative position of thediaphragm. The arrangement of control for the fuel valve 60 embodies anovel lever tially vertical portion 70 and a tubular or curled portion71 at its end region, the latter surrounding or embracing the pin 65.The L-shaped lever 68 is of the second order of lovers and is fulcrumedat one end as shown in FIG- URE 4. The vertically disposed portion orleg 70 of the lever as shown in FIGURE 4 is in contact with the end ofthe valve body 58.

The carburetor body is formed with a recess or bore 73 to accommodate anexpansive coil spring 74, an end of which engages the horizontal portion69 of the lever 68 as shown in FIGURE 4. The port or opening 63 in thevalve seat 62 should be of comparatively small diameter and area so thatthe fuel pressure acting against the cone shaped valve portion 6E) isreduced to a minimum thereby increasing the sensitivity of the fuel flowcontrol system.

The distal end region of the portion 69 of lever 68 engages a head 76 ofa rivet or member 77, the shank of which extends through openings in acomparatively thin metal reinforcing disk 78, the diphragm 40, and awasher 79, the opposite end of the rivet being swaged as at 80 to securethese components in assembled relation.

It will be apparent from examination of FIGURE 4 that when the diaphragmis flexed toward the mixing passage, the head 76 swings the lever 68 ina clockwise direction about its fulcrum 65, moving the vertical por-'tion in a generally left-hand direction permitting the valve member 58to move in a left-hand direction and facilitate flow of fuel through theport in valve seat 63 into the diaphragm chamber 38.

Such action compresses the spring 74 and, when the pressure is increasedin the diaphragm chamber 38, the spring swings the lever 68 in acounterclockwise direction to bias the valve 60 toward closed position.The upper wall of the fuel chamber 38 is formed with an elongated recessto accommodate swinging movements of the portion 69 of the lever 68.

It should be noted that the diaphragm chamber or fuel transfer chamber38 is not vented to the atmosphere and fuel from the chamber or passageisdelivered into the mixing passage by engine aspiration 'or reducedpressure in the mixing passage acting upon the fuel chamber 38. Hencethere is no predetermined or defined fuel level in the chamber 38 and,as the chamber is comparatively shallow being only sufiicient toaccommodate movement of the diaphragm 40, a minimum of fuel is containedin the chamber 38 the weight of which has a minimum influence upon theoperation of the diaphragm 40.

A main fuel orifice 84 is formed in a projection 85 extending a shortdistance into the choke band area 15 of the Venturi 14 and forms a mainfuel discharge orifice, outlet, port or nozzle for delivering fuel intothe mixing passage. The charge forming apparatus or carburetor includesa secondary fuel discharge or deliverysystem including an idling orifice86 and a low speed orifice 88 formed in a wall region of the mixingpassage, the idling 6 orifice being slightly forward of the closedposition of the throttle valve 30 as illustrated in FIGURE 3 forsupplying fuel into the mixing passage for engine idling purposes.

An auxiliary chamber 90 is formed in the carburetor body and theorifices 86 and 88 are in communication with the chamber 90, the end ofthe chamber 90 being closed by a Welsh plug or disk 92. Formed in thecarburetor body is a bore or duct 94, the end adjacent the chamber 38being closed by a cap 95. Also formed in the body is a duct or bore 96,the end adjacent chamber 38 being closed by a cap 97. The ducts 94 and96 are connected by a communicating channel 98 formed by drilling fromthe air inlet end of the carburetor, the end of the duct 98 at the rightside of the bore 94 as viewed in FIGURE 3 being closed by a plug 100.

As illustrated in FIGURES 5 and 6, the carburetor body 10 is formed witha boss portion 102 which is bored and a wall portion threaded toaccommodate a manually adjustable valve member 104 provided with aknurled head 105 for manipulating the valve body.

The bore 106 accommodating the valve body is in communication with thechamber 38 by means of a passage or channel 108 as shown in FIGURE 6,and the bore 106 is in communication with the duct 94 by means of arestricted passage 110.

The valve member 104 'is provided with a tapered or needle shaped valveportion 112 which extends into the restricted passage and provides amain adjustment for metering fuel supplied to both the main orifice 84and the secondary orifices 86 and 88. The body 10 is formed with a bossportion 116 provided with a bore 117 a wall'portion of which is threadedto accommodate a second threaded valve body 118, the latter being formedwith a knurled head 120 for manually adjusting the same.

The bore 117 is in communication with duct 96 by a restricted passage122, the valve body 118 being provided with the tapered or needle valveportion 123 which cooperates with the restricted passage 122 to meter,regulate or control fuel flow from the duct 98 and bore 96 to thesecondary orifices 86 and 88. -Coil springs 124 surround the portions ofvalve members 104 and 118 and provide friction to 'retain the valvemembers in adjusted positions. Sealing rings 125 surround the valvemembers 104 and 118 to prevent leakage.

A drilled passage or channel 126 is in communication with the bore 117and the supplemental chamber 90 as shown in FIGURE 5. The passage 126 isformed by' drilling through a boss portion 127 as shown in FIGURE 5, andthe entrance closed by a plug 128. The needle valve 123 controls thefiow or delivery of fuel into the supplemental chamber 90 for dischargethrough the orifices 86 and 88.

As shown in FIGURE 3, an air bleed passage 130 may be disposed incommunication with the air inlet region 16 and the channel or duct 94for admitting air into the fuel to form an emulsion for dischargetherewith through the main nozzle 84. In certain installations it may bedesirable to omit the air bleed passage 130 depending upon theparticular use of the carburetor.

The operation of the carburetor or charge forming apparatus shown inFIGURES 1 through 7 is as follows: In starting the engine, the chokevalve 21 is moved to near closed position and the throttle valve 30moved to partial or full open position. When the engine is cranked, reduced pressure or aspiration is set up in a mixing passage which istransmitted to the diaphragm chamber 38, flexing the diaphragm towardthe mixing passage and opening the inlet valve to admit fuel to chamber38 and cause fuel flow from the diaphragm chamber 38 past the valve 112through restricted \passage 110into the duct 94, the fuel beingdischarged into the choke band 15 of the Venturi through the mainorifice or primary outlet 84.

Some air is bled into the fuel in the duct 94 through the air bleedpassage 130 forming an emulsion.

After,

the engine is started, the choke valve 21 is progressively moved to openor near open position as the engine becomes heated. During operation ofthe engine at intermediate or high speeds, fuel is continuouslydelivered through the main orifice 84 into the mixing passage.

Through contact of the button or head 76 of the rivet 77 with the arm 69of lever 68, the lever is swung by upward movement of the diaphragm in aclockwise direction about its fulcrum 65 as viewed in FIGURE 4, movingthe angle portion 79 of the lever in a left-hand direction andpermitting the valve body 58 to move in a left-hand direction admittingfuel from the supply through fitting 54, the port in valve seat 63 intothe diaphragm chamber 33 for delivery into the mixing passage.

The valve 112 may be adjusted by manipulation of the knurled knob 105 tometer, regulate or control the maximum fuel flow to both the primary andsecondary fuel discharge system. When the engine is operating at idlingspeed with the throttle valve 36 in substantially closed position asshown in FIGURE 3, fuel flows from the duct 94 through the duct orchannel 98, bore 96, restricted passage 122 past the tapered valve 123through the channel 126 and supplemental chamber 90 to the idlingorifice 86.

When the throttle 34} is moved to partial open position, fuel may bedelivered from the low speed orifice S8 and the idle orifice 86. Duringdelivery of fuel through the idle orifice, the low speed orifice 88 orboth, the pressure in the Venturi 14 is high enough whereby fuel is notdelivered through the main orifice 34 until the engine speed increasesthrough further opening movement of the throttle 30 and air flow throughthe Venturi 14 is increased to set up a substantially reduced pressureeffective on the nozzle 84 to initiate fueldelivery from the main fuelorifice 84.

As the engine speed increases, delivery of fuel through the secondaryorifice system, that is, through orifices 86 and 88 gradually diminishesand at high engine speeds only a small proportion of the fuel isdelivered through the secondary orifice system. The needle valve 123 maybe adjusted by manipulating the knob 120 to regulate or meter fuel flowto'the supplemental chamber 90 of the secondary fuel discharge system,the valve member 112 however regulating the maximum amount of fuel fordelivery through the main orifice as well as through the secondaryorifice system.

, During engine operation, a subatmospheric or reduced pressure existsin the diaphragm chamber 38 by reason of the aspiration of the enginesetting up air flow through the mixing passage of the carburetor.Through this action the relative position of the diaphragm 40 isinfluenced by the amount of reduced pressure in the chamber 38 toregulate the extent of opening of the inlet valve 60 and therebyregulate the amount of fuel entering the diaphragm chamber 38 inaccordance with the requirements of the engine.

The higher the air velocity through the Venturi 14, the greater will bethe reduced pressure effective in the chamber 38, and a proportionatelygreater amount of fuel will be withdrawn from the reservoir or diaphragmchamber 38 into the mixing passage 12. A reduction in pressure in theVenturi 14 is transmittedthrough the bore or channel 94, passages 110and 108 to the diaphragm chamber 38, elevating the diaphragm 40 agreater distance and hence effecting increased movement of the valve 60toward open position, thereby increasing the flow of liquid fuel fromthe supply into the carburetor.

Where the air passage 130 is employed, air bleeds intothe fuel in theduct 94 and a fuel emulsion is delivered through the main orifice 84.When the engine idling orifice 86 is in operation, or the idling orificeand they low speed orifice 88 are in operation, an emulsion of fuel andair is delivered through the secondary orifice system as air bleeds intothe duct 94 from the mixing passage -character as that shown in FIGURE3.

through the main orifice 84 due to the fact that the pressure in theVenturi, with the throttle 30 in closed or nearly closed position ishigher than the pressure at the lefthand or engine side of the throttle30 as viewed in FIG- URE 3.

The extent or amount of air bleeding through the main nozzle 84 isgreatest at low engine speeds and such air bleeding is progressivelyreduced as the engine speed increases and the aspiration at the Venturi14 increases. Through this type of metering system, the secondaryorifices 86 and 88 may be made appreciably larger than conventionalpractice where the mixture supplied thereto is air bled as hereindescribed. This renders the idling orifice and idling mixture lesssensitive and fosters better idling of the engine.

The L-shaped or angle lever 68 provides for a compact fuel inlet controlsystem and is apparently more stable especially at high engine speeds.This is attributable to the fulcrum position of the lever being at oneend while the opposite end region engages the head 76 secured to thediaphragm so that vibratory movement or a tendency toward vibratorymovement of the lever is dampened by the diaphragm. This is ofparticular advantage where the carburetor is utilized with lawnmowerengines where the mower traverses rough terrain and is subjected tosubstantial vibration.

Another form of the Charge forming apparatus of the invention isillustrated in FIGURES 8 through 13. In this form the carburetor body isof substantially the same shape as that shown in FIGURE 1, and thediaphragm and lever arrangement for controlling the fuel flow into thecarburetor is substantially the same as that hereinbefore described inconnection with the form shown in FIGURES 1 through 7.

In this form the carburetor body 10a is provided with an air inletregion 16a, an air outlet region 18a and a mixing passage 12a. Themixing passage includes a Venturi 14a having a band or zone of maximumrestriction a. The air inlet is provided with a choke valve 12a mountedon a rotatable shaft 22a, and the mixture outlet 18a provided with adisk type throttle valve a mounted upon a rotatable shaft 28a.

The carburetor-body 10a is formed with a shallow chamber or fuel passage38a, one wall of which is formed by the diaphragm 49a, the diaphragmbeing of the same A sheet metal cover plate 44a for the diaphragm issecured to the body 10a by means of screws 45a. The central region ofthe plate 44a is depressed providing a vented chamber 460 accommodatingmovement of the diaphragm 40a.

With particular reference to FIGURE 12, the construction is inclusive ofa fuel inlet fitting 53a, a sleeve or fitting 56a which encloses aported valve seat 62a. A valve body 58a is slidably accommodated withinthe hollow interior of the sleeve 56a, the valve body having a needlevalve portion 60a cooperating with the valve seat 62a.

An L-shaped or angle lever 68a fulcrumed upon pin a has its distal endin contact with the head 76a of member 77a secured to the diaphragm 40a.An expansive coil spring 74a serves to bias the lever 68a in a directionto urge the valve 60a toward closed or fuel flow interrupting position.The lever 68a is of the second order of levers, being fulcrumed at oneend as illustrated in FIGURE 12,.

The fuel metering system and channels for conveying fuel from thediaphragm chamber 38a for delivery into the mixing passage include aduct or passage 94a which receives fuel from the chamber 38a throughpassages 108a, 106a and 110a, these passages being shown in FIGURE 10.The adjustable needle valve 112a, which is manipulated by a knurled knoba, is arranged to meter, regulate or control the fiow of fuel fromchamber 38a into the duct 94a for delivery into the Venturi 14a of themixing passage through the main nozzle or orifice 84a.

The secondary fuel delivery system includes an idling orifice 860, a lowspeed orifice 88a, the supplemental chamber 90a and fuel passage 126a incommunication with the bore 117a as shown in FIGURE 13. The bore 117a isin communication with the bore 96a through a passage 122a. A needlevalve 1230, which may be adjusted by manipulation of a knob 120aregulates or controls the fuel flow to the chamber 90a for deliverythrough the secondary discharge orifices.

The fuel for the secondary orifice system is obtained by way of apassage 135 in communication with the bore 96a and the bore 106a whichaccommodates the body portion of the valve 112a as shown in FIGURE 13.The passage 135 is formed by drilling into the body of the carburetor inan angular direction shown in FIG- URE 13, and the entrance of thedrilled opening closed by a plug 137. It should' be noted that the fuelsupplied to the secondary orifice system is obtained from the diaphragmchamber 380 through the passage 108a, the bore 106a and passage 135independently of the fuel flow to the duct 94a.

Thus the fuel delivered to the high speed orifice 84a is controlled ormetered by the valve member 1120, While the fuel delivered to thesecondary orifices is controlled or metered solely by manipulation ofthe valve 123a. In the several forms of the invention disclosed herein,the diaphragm or fuel chamber is disposed as close as possible to themixing passage inorder to reduce the lift or aspiration required toelevate fuel through the discharge orifices into the mixing passage.

In the form of the invention illustrated in FIGURES 8 through 13, .thefuel metering and conveying system for the main orifice 84a include apassage or passages of such size as to establish a liquid seal providedby the capillary action of the liquid fuel. This feature is ofparticular importance under certain operating conditions as it preventsair bleeding in reverse direction through the main orifice 84a to thesecondary orifices 86a and 880 when the latter are delivering fuel intothe mixing passage.

This enables the carburetor or-charge forming apparatus to be operatedin extreme angular positions. The principles of operation of a capillaryseal or liquid seal arrangement are disclosed and described in my Patent2,841,372 granted July 1, 1958.

In the arrangement shown in FIGURES 8 through 13, Q

a liquid or capillary seal tends to form in the main orifice 84a and inthe annular area at the region surrounding the needle valve 112a betweenthe cylindrical wall of the valve passage 110a and the adjacentperipheral region of the needle valve 112a. 'It is found that the liftfor usual operation of the carburetor is that pressure which willsupport a column of water about three-eighths of an inch in heighth,which is substantially under the maximum stress at which the seal orcapillary seal will be fractured or broken.

It is found that the liquid seal due to the capillary effect of fuel inthe metering passage 110a and in the main orifice passage 84a iseffective without fracture up to a pressure required to support a columnof water about one inch in heighth. As the differential pressure usuallypresent in chamber 38a during operation of the carburetor isapproximately that pressure required to support a column of waterthree-eighths of an inch in heighth, the normal operation is well withinthe pressure limit to maintain a liquid or capillary seal in the highspeed fuel delivery system effective to prevent back bleeding from themixing passage through the main orifice 84a and into the secondary fueldelivery system.

The fuel in the main orifice 84a and in the annulus surrounding theneedle valve 112a in the restricted passage 110a seals or blocks airflow from the mixing passage into the secondary fuel delivery system.Through this arrangement the carburetor may be operated at engine idlingand low speeds in extreme angular positions as fuel will be preventedfrom flowing by gravity through the main orifice 84a into the mixingpassage by the liquid or capillary seal.

The operation of the arrangement shown in FIGURES 8 through 13 is asfollows: The engine is started by closing the choke valve 21a andopening the throttlevalve 30a and cranking the engine. After starting,the choke valve 21a is opened. Fuel is delivered through the high speedorifice 84a into the mixing passage 12a, the fuel being supplied fromthe diaphragm chamber 38a through passages 108a, 106a and a and duct94a. The fuel delivered to the main orifice 84a is metered or regulatedby adjusting the position of the valve 112a, this valve metering orregulating only the fuel flow tothe main orifice 84a.

When the throttle 30a is in substantially closed to engine idlingposition, the secondary orifice 86a delivers fuel for engine idlingpurposes from the chamber 90a. When the throttle is partially opened,fuel is delivered from the low'speed orifice 88a as well as the idlingorifice 86a. The fuel supplied to the secondary orifices 86a and 88a isregulated or metered solely by the position of the valve 123a as thesecondary orifice system derives its fuel supply from the diaphragmchamber 38a independently of the valve 112a.

When the throttle 30a is in full open or substantially open position,the aspiration in the Venturi 14a is increased by higher engine speedand the liquid or capillary seal provided by the fuel in the mainorifice 84a and adjacent the valve 112a is broken by the substantialreduction in pressure effective on the orifice 84a whereby fuel isdelivered through the high speed orifice 84a into the mixing passage,and the percentage of fuel delivered through the secondary orifices 86aand 88a is progressively reduced with increased engine load and speed.

In idling or low speed engine operating positions of the throttle 30a,the pressure effective in the diaphragm chamber 38a is insufficient tofracture the capillary seal -thus preventing back bleeding of airthrough the main orifice 84a into the secondary fuel delivery system.The fiexure or movement of the diaphragm 40a controlled by the degree ofreduced pressure or aspiration in the mixing passage is operable throughthe lever 68a to regulate the fuel flow from a supply past the inletvalve 60a in the same manner as hereinbefore described in connectionwith the form of the invention shown in FIGURES 1 through 7.

An air bleed a shown in FIGURE 9 may be employed to admit air into theduct or passage 94a for mixing with the fuel prior to its deliverythrough the main orifice 84a into the mixing passage. It is to beunderstood that in certain uses or installations of the carburetor, theair bleed 130a may be omitted. The air bleed 130a is of comparativelysmall size and therefore has no appreciable effect upon the formationand maintenance of the capillary or liquid seal in the high speed fueldelivery system.

In the arrangement as illustrated in FIGURE 13 the secondary fueldelivery system receives fuel through the passage in communication withthe bore 106a which receives fuel from the diaphragm chamber 38a throughthe passage 108a. It is to be understood that the fuel for the secondaryfuel delivery system may be obtained through direct communicationbetween the bore 96a and the diaphragm chamber 38a by eliminating theclosure 97a or forming an opening in the closure.

In either arrangement, the liquid seal which forms under the conditionshereinbefore described in the main orifice 84a and the annular regionadjacent the valve 112a is effective to prevent back bleeding of airthrough the primary or high speed delivery system Another form ofcarburetor of the invention is illustrated in FIGURES 14 through 19. Asignificant feature of the arrangement shown therein is the provision ofa double Venturi construction in the mixing passage. In this form, thebody 140 of the carburetor is of the same general configuration as inthe forms of the invention hereinbefore described. The arrangementincludes an air and fuel mixing passage 1212 having an air inlet region16b and a mixture outlet region 18b at the end of a carburetor adaptedto be connected with an engine crankcase or intake manifold.

The mixing passage is inclusive of a main Venturi 14b having a band orzone of maximum restriction 15b. Formed within the lower portion of themain Venturi as viewed in FIGURE 15 is a generally cylindricallyshapedboss portion 142, the uppermost surface region of which is subtsantiallycoincident with the axis of the main Venturi. I

The boss portion 142 is of hollow configuration and is shaped interiorlyto form a second or supplemental Venturi 144, the inlet region of whichopens into the air inlet region 16b.

The supplmental Venturi is provided with a choke band or zone of maximumrestriction 146, the outlet end 148 of the supplemental Venturi openingtoward the mixture outlet 18b, and the lower interior surface definingthe outlet region 148 blending with the lower outlet surface of the mainVenturi 14b. The main orifice 84b of the primary fuel delivery systemopens into the supplemental Venturi 144 at a region in or adjacent thezone of maximum restriction 146. This arrangement provides improveddistribution of the fuel in the air streams moving through both the mainand supplemental Venturis.

The air inlet region 16b is equipped with a choke valve 21b mounted upona rotatable shaft 22b, and the mixture outlet region 1811 is providedwith a throttle valve b mounted upon a rotatable shaft 28b, the throttlebeing shown in near closed or engine idling position in FIG- URE 15. Asin the other forms of the invention, the carburetor is for-med with ashallow fuel or diaphragm chamber 3812, one wall of which is formed bythe flexible diaphragm b. The diaphragm is held in place by a coverplate 44b secured to the carburetor body by screws 45b, the plate 44bhaving a depressed central region forming a vented chamber 46baccommodating movement of the diaphragm.

As shown in FIGURE 18, the carburetor is provided with a threaded boreto receive an inlet fitting 53b adapted to be connected by tubular meanswith a fuel supply.

The bore also accommodates a fitting or sleeve 56b in which is slidablysupported an inlet valve body 58b formed with a cone shaped valveportion 69b adapted to cooperate with a ported valve seat 62b. AnL-shaped lever 68b is fulcrurned at one end by a pin or shaft b,

the distal end of the lever being in contact with a head or button 76bprovided on a member 77b carried by the diaphragm 4012. An expansivecoil spring 7 11; biases the lever 68b in a counterclockwise directionto normally urge the valve 60b toward the valve seat 62b.

The fuel duct system for conveying fuel from the diaphragm chamber 33bto the mixing passage includes a main or primary orifice or nozzle 34bin communication with a duct 94b as shown in FIGURE 15. The high speedor primary nozzle 84b receives its fuel from the diaphragm chamber 331?through passages 10812, 106b and 11017 as shown in FIGURE 17. Disposedin the passage 11Gb is a valve body provided with a needle valve portion11212 which cooperates with the restricted passage 11Gb for metering orregulating fuel flow to the main nozzle 84]). The valve 11012 isprovided exteriorly of the carburetor with a knurled knob 10511 foradjusting the valve.

The s condary fuel delivery system includes an idling orifice 86b and alow speed orifice 2-812 opening into a supplemental chamber @911. Thechamber 90b is in cornmunication with a bore 117]) as shown in FIGURE19, the bore 1171) being in communication with a bore through arestricted passage or channel 122b. The bore 150 opens into the fuel ordiaphragm chamber 38b as shown in FIGURE 15. A needle valve 12311carried by a valve body threadedly disposed in the bore 11711 isprovided with a knurled knob 1201) for adjusting the valve 12312.

By adjusting this valve, the fuel flow to the secondary fuel deliverysystem comprising orifices 86/) and 83b is metered by adjusting therelative position of the needle shaped valve 12317 in the passage 1221;.The high speed orifice 84b is supplied with fuel from chamber 38bindependently of the fuel supplied to the secondary orifices 86b and881). An air bleed passage 1301) shown in FIGURE 15 may be utilized incommunication with the air inlet 16b and the bore 94b for admitting airinto the fuel prior to its discharge through the main orifice 84b.

The operation of the carburetor or charge forming apparatus shown inFIGURES 14- through 19 is as follows: The engine is started in the samemanner as described in connection with the other forms of the inventionby closing the coke valve 21b and opening the throttle valve 30b. Fuelis delivered through the main orifice 84b with the throttle 30b insubstantial open position, the fuel supplied to the main orifice flowingfrom the chamber 33b through passages 108b, 106b and 11Gb past theregulating or metering valve 112b and bore 94b through the dischargeorifice 84b and into the smallor supplemental Venturi 144.

Th1s action continues during moderate and high speed engine operation.The fuel and air mixture in the supplernental Venturi 144 is distributedthrough the outlet region of the primary or main Venturi 14b so that ahomogeneous mixture of air and fuel is delivered through the mixtureoutlet 18b to the engine. When the throttle valve 30b is in near closedor engine idling 'POSIIIOH or opened to secure low speed engineoperation, fuel is delivered through one or both of the secondaryorifices 86b and 88b. The chamber 9012 receives fuel through passages1261), 117b, 1221) and bore 150 from the fuel chamber 38b independentlyof the high speed orifice system.

Under the influence of the reduced or subatmospheric pressure in themixing passage, the diaphragm 40b is flexed toward the mixing passage,such action moving the lever 6812 about its fulcrum to permit opening ofthe valve 6% admitting fuel from a supply into the chamber 38b, theextent of movement of the diaphragm and hence the rate of fuel flow intothe chamber being dependent upon the rate of fuel delivery into themixing passage.

The arrangement shown in FIGURES 14 through 19 embodies a capillary orliquid fuel seal for the main orifice when either or both of thesecondary orifices are in operation. As shown in FIGURE 17, the valve1121) cooperates with the restricted passage 11% to meter the deliveryof fuel through the main orifice 8411.

However when the pressure is increased in the supplemental and primaryVenturis by reducing the throttle opening bringing the secondaryorifices 86b or 88b into operation, the capillary action of the fuel inthe main nozzle and the annular region around the needle portion of thevalve 11212 in the passage 11% sets up or establishes a liquid sealpreventing reverse flow or back bleeding of air from the mixing passageinto the unvented diaphragm chamber 38b.

Hence this form of carburetor will function in extreme angular positionsas the diaphragm 40b is controlled solely by aspiration in the mixingpassage. The double Venturi arrangement as illustrated provides improvedengine operation particularly at open throttle operation under heavyloads.

While the supplemental Venturi is preferably disposed in the mainVenturi at a region close to the diaphragm chamber 3812 so as to beoperable with minimum lift, it may be disposed at other positions in themixing passage if desired.

FIGURES through illustrate a modified form of carburetor of theinvention. The carburetor body 1400 is provided with a mixing passage120 which includes an air inlet region 160, a primary or main Venturi158, a supplemental Venturi 1440 and a mixture outlet 180. The air inletregion 160 is provided with a choke valve 210 mounted upon a rotatableshaft 220 and the mixture outlet region 180 provided with a throttlevalve c mounted upon a rotatable shaft 28c.

The carburetor body 1400 is formed with a shallow fuel or diaphragmchamber 38c, one wall of the chamber 380 being formed by the flexiblediaphragm 40c of the same construction as in the other forms of theinvention hereinbefore described. The diaphragm 400 is held in place bya cover plate 44c secured to the carburetor body by screws 450. Thecentral region of the cover plate 440 is depressed to provide a ventedchamber 460 accommodating flexing movements of the diaphragm 400.

The diaphragm 400, being under the influence of aspiration in the mixingpassage 120, controls the fuel inlet valve arrangement shown in FIGURE24 for admitting fuel from a supply into the chamber 38c. A nipple orfitting 53c, threaded into a bore in a boss portion of the carburetor,is adapted to connected by a flexible tube or other tubular means with afuel supply.

Also disposed in the bore receiving the fitting 530 is a sleeve 560, thehollow interior thereof accommodating a movable valve body 58c providedwith a cone shaped valve portion 600. The sleeve 560 is provided with arecess accommodating an annular valve seat member 620 through which fuelmay flow past the valve 600 into the chamber 380.

As shown in FIGURE 24, the fuel flow control arrangement includes theL-shaped lever 68c fulcrurned at one end by a shaft or pin 650, thedistal end of the lever being in engagement with a head 760 of a rivetor member 77c carried by the diaphragm 400. The vertical portion of thelever 68cengages the end of the valve body 580. An expansive coil spring74c engages the lever 68c to bias the lever toward valve-closingposition.

Disposed in the region of the mixing passage nearest to the diaphragm400 is a cylindrical boss portion 142C in which is fashioned asupplemental or small Venturi 1440 having a choke band or region ofmaximum restriction 146C. The main orifice or outlet 84c opens into thechoke band 1400 of the supplemental Venturi and is in communication witha duct or passage 164 formed in the body 1400. Pressed or fitted intothe duct 164' is a I thin metal sleeve or fitting 160 formed at itslower end with an inwardly extending peripheral flange 161.

The fitting 160 is disposed in the upper end of the duct or bore 164 andencloses a ball check member or valve means 162. The flange 161 forms aseat for the valve 162 and defines a central circular opening of smallerdiameter than the diameter of the check valve 162 whereby the checkvalve is normally maintained Within the fitting.

It should be noted that the axis of the duct 164 and hence the normalaxis of position of the check ball 162 is eccentric with or spacedlaterally from the axis of the main 'orifice 84c so that irrespective ofthe position of the check ball 162 Within the fitting 160 the check balldoes not block or impede the flow of liquid fuel from the duct 164 tothe main orifice or outlet 84c into the supplemental Venturi 1440. Theball 162 forms a valve means for closing the opening in the fitting 160defined by the flange 161 preventing back bleeding of air from themixing passage in a reverse direction through the orifice 84c.

The secondary fuel discharge system includes an idling orifice 86c and alow speed orifice 880, both being in communication with a supplementalchamber 900. The supplement-al chamber 900 is in communication with abore knurled knob 1200 for adjusting the relative position of the needlevalve 1230. By this means, fuel flow to the secondary orifice system ismetered or regulated by adjustment of the valve 1230. The d-uct 168 isin communication with the duct 164 by a passage .166, the latter beingdrilled from the air inlet end of the carburetor and the entrance closed:by a plug 169 as shown in FIGURE'ZI.

With particular reference to FIGURE 23, a threaded bore 166a receives avalve body formed with a needle valve portion 11120 which extends into arestricted passage M06 in communication with the bore 106s and the duct164. The valve body of the needle valve 1120 is provided with a knob.10'Sc for adjusting the relative position of the needle valve :1120.The bore 106c is in. communication with the diaphragm chamber 38cthrough a passage 108C.

Fuel is delivered into the passage or duct 164 through v the passage168e, bore 106a, past the needle valve 1 and through the restrictedpassage 110c. The valve 1120 is adjusted to a position in accordancewith the fuel requirements of the engine. It should be noted that theneedle valve 112a regulates or meters the fuel for delivery both throughthe main orifice 84c and through the secondary orifices 86c and 880, andthe needle valve 1230 provides a secondary adjustment for fuel flow tothe secondary orifice system.

An air bleed c between the air inlet region and the duct 164 shown inFIGURE 21 is adapted to bleed air into the fuel in the duct I164 foradmixing with the fuel discharged through the main and secondaryorifices. As stated in connection with other forms of the invention,under certain uses of the carburetor the air bleed 1300 may be omitted.

The check ball 162 is preferably fashioned of lightweight material asfor example a resinous material such as nylon, a polyamid resin, orDel-rin, a formaldehyde resin. Through the use of a check ball 162 as avalve of lightweight material, the ball is readily lifted from its seaton the flange 16']. under the influence of asipration or reducedpressure in the mixing passage.

The operation of the carburetor or charge forming apparatus shown inFIGUR'ES 20 through 25 is as follows: The engine is cranked while thechoke valve is closed and the throttle valve 30c opened. The aspirationset up in the mixing passage moves the diaphragm 40c permitting fuelfrom a supply to flow past the inlet valve 69c into the chamber 38cthence through the passages 1080, 106e, 1100 and duct 164, upwardlypas-t the ball valve 162 and discharged through the main orifice 84 intothe supplemental or small Venturi 1440.

The air and fuel mixture formed in the small Venturi flows into the airmoving through the primary or main Venturi 15% providing a fuel and airmixture. The extent of flexure or upward movement of the diaphragm 40cis dependent upon the amplitude of aspiration or reduced pressureestablished in the mixing passage 120 .by the speed of the engine. Theextent of diaphragm movement controls the extent of opening of the valve600 and hence the flow rate of fuel into the diaphragm fuel chamber 380.

When the throttle valve 300 is in engine idling position as shown inFIGURE 21, or in partial open low speed position, the fuel from the duct164 flows to the secondary orifices 86c and 88c through the channels orducts 166, 1168, restricted passage 1222c past the needle valve123cthrough passage 1260 into the chamber 90c. During operation of thesecondary fuel delivery system, back bleeding of air from the mixingpassage through the main or primary orifice 84c is prevented by the ballcheck member 162 is disposed on the seat provided by the fiange. Airfrom the air bleed passage 1300 is supplied to the fuel forming anemulsion for delivery through the orifices.

The fuel flow control for both the main orifice 84c and the secondaryorifices is provided through the adjustable needle valve 1112c, and :asecondary adjustment for the fuel delivered through the secondaryorifices is provided by needle valve 123c. Both valves are manuallyadjustable by manipulating the grip portions 1415c and 12130. Thecarburetor illustrated in FIGURES through has particular utility wherethe engine is subjected to heavy load conditions at comparatively lowspeeds such as encountered in garden tractors or a motorcycle enginepropel-ling a motorcycle up a steep incline.

If it is desired to provide a fuel emulsion for delivery through themain nozzle 84c only, the air bleed 130s may be drilled to enter thesleeve 160 at a zone above the flange 161 so that air bleeding of thefuel discharged through the main orifice 840 takes place within thesleeve 160. Where such modification is employed, the fuel will bedelivered from the duct 164 through the secondary orifices withoutadmission of air into the fuel prior to its delivery into the mixingpassage.

Another modification of the carburetor of the invention is illustratedin FIGURES 26 through 31. In this arrang'ement, the carburetor body 10:!is formed wit-h a mixing passage 12d which includes a Venturi 14d havinga choke band or maximum zone of restriction 15d, an air inlet region 16dand a mixture outlet region 18d. The air inlet region of the mixingpassage is provided with a choke valve 2|1d mounted upon a rotatableshaft 22d, and

the outlet region of the mixing passage provided with a throttle valve dmounted upon a rotatable shaft 28d.

The canburetor body is fashioned with a shallow fuel chamber 38d, adiaphragm 40d forming one wall of the fuel chamber. The diaphragm isheld in place by a cover plate 44d secured to the body by screws 45d,the central region of the closure member 44d being depressed providing achamber 46d accommodating fiexure or movement of the diaphragm 40d.

The .fuel inlet control arrangement operated by movement of thediaphragm 40d is illustrated in FIGURE 30 and is inclusive of a nippleor fitting 53d threaded into a bore in the carburetor body and which isadapted to be connected by means of a flexible tube or other means witha fuel supply.

Also threaded into the bore accommodating the fitting 53a is a tubularmember or sleeve 56d, the hollow central region slidably accommodating avalve body 58d, the body having a conically shaped valve portion 69d.The sleeve 56a is formed with a recess accommodating a ported valve seat62d which is held in place by the fitting 53d.

The L-shaped lever 68d, fulcrumed at one end upon the shaft 65d, has itsdistal end engaging the head 76d of member carried by the diaphragm 40a.The vertical leg portion of lever 68d engages the end of the valve body53d. An expansive coil spring 74d engaging the lever 68:! normallybiases the lever in a counterclockwise direction urging the inlet valve60d toward the valve seat 62a. The arrangement shown in FIGURES 26through 31 is inclusive of an accelerating well or a fuel reservoirwithin the carburetor between the fuel chamber 38d and the main fueldischarge orifice 84d.

With particular reference to FIGURE 27 the carburetor body is formedwith a bore or chamber 181, the upper end region of which is of reduceddiameter and into which is pressed or disposed a tubular fitting ormember 175. The tubular fitting 175 is provided with a sleeve or hollowshank portion 179 of lesser diameter which depends or extends downwardlyinto the chamber 181, the portion 179 terminating a l19t distance abovea Welsh plug 180 isolating the chamber 181 from direct communicationwith the diaphragm or fuel chamber 38d.

The upper portion of larger diameter of the fitting or tubular member175 accommodates a valve means in the form of a check ball 177, which isof a diameter slightly larger than the diameter of the interior region183 defined by the depending portion 179 of the sleeve. The region ofreduced diameter of the tubular member 175 at the juncture of thedepending portion 179 therewith provides a seat for the ball check valve177, the latter functioning to prevent back bleeding of air from themixing passage through the main orifice 84d when the secondary fueldelivery system is in operation.

The check ball or valve member 177 is preferably formed of lightweightmaterial as for example a resin such as nylon or Delrin or othersuitable material. The secondary fuel delivery system includes an engineidling orifice 86d, a low speed orifice 88d, both of which are incommunication with a supplemental chamber 90d. The supplemental chamber90d is in communication with a threaded bore 117d by means of a passage12601, the bore 117d accommodating a valve body member formed with aneedle valve portion 123d and a manipulating grip portion 120d.

The bore 117d is in communication with a bore or duct 168d through arestricted passage 122d, the needle valve 123d extending into and beingadjustable relative to the passage 168d for metering or regulating thefuel delivered to the secondary orifice system. The duct 168d, as shownin FIGURE 7, is in communication with the chamber 181 by means of achannel or duct 166d which is drilled into the carburetor body from theair inlet end 1601, the entrance to the drilled passage being blocked bya plug 169d.

Fuel is supplied from the chamber 38d to both the main or primaryorifice 84d and the secondary orifice system through the arrangementshown in FIGURE 29. A threaded bore 136d formed in the body is incommunication with the chamber 38d by a fuel passage 108d. The bore 106dis in communication with the chamber 181 by means of a restrictedpassage 110d. A needle valve 112d is formed on a valve body adjustablymounted within the bore 106d, the needle portion 112d extending into thepassage 1100. to regulate fuel flow into the chamber 181.

The body of the needle valve 112d is provided with a manipulating gripportion 105d for adjusting the relative position of the needle valve.The needle valve 112d controls the flow of fuel from the fuel chamber ordiaphragm chamber 38d to both the primary and secondary fuel deliverysystems.

It will be apparent from FIGURE 27 that the duct or passage 166d is incommunication with the upper end region of the chamber 181 so thatduring operation of the secondary orifices 86d or 88d the chamber 181 ismaintained filled with fuel from the reservoir 38d whereby the chamber181 form an accelerating well for subsequent rapid discharge of fuelthrough the main orifice 34d into the mixing passage 12d. In thisarrangement the aspiration effective on the secondary orifice systemelevates fuel from the chamber 38d to fill the well 181 with fuel.

it should be noted that the main or high speed orifice 84d is offsetfrom the axis of the tubular fitting 175 so that the check ball 177 doesnot at any time block the orifice 84d.

An air bleed d may be arranged between the upper end of the chamber 181and the air inlet region 16d of the carburetor to admit air into thechamber 181 for mixing with the fuel delivered through the main orifice84d after the fuel in the accelerating well 181 is substantiallyexhausted following an initial surge or discharge of fuel therefromthrough the main orifice 84a to obtain rapid acceleration of the engineby temporarily enrichening the mixture of fuel and air in the mixingpassage.

Due to the fact that the channel 166d is in communication with theextreme upper end of the accelerating well 181, the well will bemaintained substantially filled with liquid fuel whenever the secondaryorifice system is delivering fuel into the mixing passage and little orno fuel is being delivered into the mixing passage through the mainoutlet or nozzle 84d.

Thse operation of the charge forming apparatus or carburetor shown inFIGURES 26 through 31 is as follows: The choke valve 21d is closed andthe throttle valve 30d opened substantially during cranking of theengine to establish a reduced or subatmospheric pressure in the mixingpassage 12d. The reduced pressure influences the diaphragm 40d to beflexed upwardly as viewed in FIGURES 27 through 30 swinging the lever68d in a clockwise direction to permit opening of the inlet valve 60d.

Fuel flows from a supply past the valve 60d and through the fuel chamber38d into the well 181 thence upwardly through the passage 183 defined bythe sleeve portion 179 past the check ball 177 and through the primaryor high speed nozzle 84d into the air stream moving through the mixingpassage. As the engine is warmed, the choke valve 21a is progressivelymoved toward open position. Fuel for the secondary orifices 86d and 88dis conveyed from the well 181 through passages or ducts 166d, 168d,122d, 117d and 126d into the supplemental chamber 90d.

When the orifice 86d or orifice 88d or both are in operation, thepressure in the Venturi 14d is increased and the check ball 177 isseated and prevents reverse flow or back bleeding of air from the mixingpassage through the primary orifice 84d. In the metering system of thisform of the invention, the needle valve 112d regulates or controls themaximum fuel flow to both the primary and secondary orifice systems,-andsupplementary control of the fuel flow to the secondary system beingregulated by adjustment of the needle valve 123d.

When the throttle valve 30d is suddenly opened a substantial amount froman engine idling or low speed position of the throttle to accelerate theengine, the pressure in the mixing passage in the Venturi 14d isdecreased and the pressure adjacent the secondary orifices 86d and 88dis increased. Under these conditions the high aspiration in the Venturieffects rapid delivery of the fuel in the well 181 past the check valve177 and through the main orifice 84d to provide a temporarily enrichenedmixture to accelerate the speed of the engine.

Thus an amount of liquid fuel in the well 181 is available for engineaccelerating purposes at all times during operation of the secondaryorifice system. The aspiration acting on the nozzle 84d is effective tomove the diaphrgam 40d upwardly to further open the fuel inlet valve 60dand increase the flow of fuel into the fuel transfer or diaphragmchamber 38d and well 181 for continuous discharge through the mainorifice 84d duringcontinued high speed engine operation.

When the throttle is moved to closed or nearly closed position from highspeed or open throttle position, the pressure in the mixing passageadjacent the secondary orifices is reduced, the pressure in the Venturi14d is increased, fuel delivery through the main orifice 84d ceases, theball check 177 is again seated, the well 181 fills with liquid fuel andthe fuel in the well moves through the passage 166d to the secondaryorifices 86d and 88d.

The well 181 is replenished with fuel by aspiration effective at thesecondary orifices whereby an amount of fuel in the well is availablefor an accelerating charge through the main orifice 84d. Ininstallations where the air bleed 130d is employed, an emulsion of fueland air is delivered through the main orifice 84d as soon as the amountof liquid fuel in the accelerating well 181 is discharged through themain orifice 84d.

FIGURE 32 is a transverse sectional view illustrating a modification ofthe arrangement for controlling the fuel flow into the carburetor. Thecarburetor body 10 is provided with a boss 50e at one side thereofhaving a bore which is threaded to accommodate a fitting or nipple 53eadapted to be connected by means of a flexible tube with a fuel supply.

The threaded portion of the bore in the boss 50e also accommodates asleeve or hollow member 56a in which is slidably mounted a valve body58e having a cone shaped valve portion 60a. The cone shaped valveportion is adapted for cooperation with an annular valve seat 62ccontained in a recess formed in the sleeve 56:: and held in place by thefitting 53e.

A closure member 44e secures the diaphragm in place, the member 442being secured to the body We by means of screws 45e. The central regionof the plate 44:: is depressed to provide a chamber 46e to accommodateflexure of the diaphragm 40e, the chamber 46s being vented to theatmosphere.

The L-shaped lever 68:: is fulcrumed upon the pin s, the verticalportion 702 of the lever contacting the end of the valve body 582. Thehorizontal portion 69e of the lever is in contact with the head 76a of amember We carried by the diaphragm 402. The carburetor body 102 isformed with a bore in which is disposed an expansive coil spring 191. Asshown in FIGURE 32, the coil spring engages a distal end portion of thelever extending beyond the region of contact of the lever 68s with thehead 76a.

The spring 191 normally biases the lever 68e in a counterclockwisedirection about its pivot shaft or fulcrum 65s to bias the valve 602toward the valve seat 62s. The spring 191 engaging the distal end of thelever 68e facilitates the use of a proportionately lighter spring. It isto be understood that the fuel inlet control mechanism shown in FIGURE32 may be utilized with any of the forms of carburetor hereinbeforedescribed.

FIGURE 33 is a transverse sectional View illustrating a modified form offuel inlet valve control system for regulating the flow of fuel into adiaphragm chamber. The carburetor body 195 is formed with a boss portion198 which is provided with a bore accommodating a hollow sleeve 200, theaxis of the sleeve being substantially normal to the plane of theflexible diaphragm 226. The

sleeve 200 is positioned within the bore by means of a ledge 202, agasket 204 being disposed between the end of the sleeve and the ledge202.

The lower end of the sleeve 200 is formed with an inwardly extendingflange 205 which defines a seat for a cone shaped inlet valve member 208which is secured upon a rod 206. The upper end region of the sleeve 200is recessed to accommodate a plate 210 formed with openings tofacilitate flow of fuel and a central opening forming a guide means forthe rod 205. A coil spring 212 is disposed within the interior of thesleeve 200, the upper end engaging the plate 210 which is pressed intothe recess in the sleeve 200, the other end of the spring engaging thevalve member 208, the spring normally urges the valve member toward theseat provided by the flange 205.

Also threaded into the boss portion 198 is a fitting 216 adapted to beconnected by a tubular means with a fuel supply or fuel tank. A flexiblediaphragm 226 forms one wall of the shallow fuel chamber 225, thediaphragm being of similar construction to that shown in the other formsof the invention.

A cover plate 230 for the diaphragm is secured to the body by means ofscrews 231, one of which is shown in FIGURE 33. The central portion ofthe cover plate 230 is depressed to form a chamber 232 accommodatingflexure or movement of the diaphragm 226, the chamber being vented as at234.

A lever 220 of the second order of levers is disposed so as to transfermovements of the diaphragm to the Valve member 208 through contact ofthe lever with an end of the rod 205. The lever 220 is fulcrumed at oneend upon a pin 224, a curled or cylindrical portion 222 of the leverembracing the pin 224. The distal end of the lever 220 engages a head228 of a member carried by the diaphragm 226. The rod 206 engages thelever at a region between its fulcrum 222 and the point of engagement ofthe lever with the head 228.

The arrangement shown in FIGURE 33 for controlling the flow of liquidfuel into the chamber of the carburetor may be used with any forms ofthe carburetor hereinbefore described. The diaphragm 226 is flexed byaspiration or differential pressure existing in the mixing passage 196in the same manner as hereinbefore described in connection with theother forms of the invention. When the diaphragm 226 is flexed upwardlyby engine aspiration, the lever Z moves in a clockwise direction aboutits fulcrum 224 elevating the cone shaped valve member 208 from the seatprovided by the flange 206 to permit fuel flow through the fitting 216,the hollow interior of the sleeve 200, past the valve 208 into thediaphragm or fuel transfer chamber 225.

The main and secondary orifice systems hereinbefore described in theother forms of the invention may be utilized in conjunction with thefuel inlet control system shown in FIGURE 33. The pressure of theexpansive coil spring 212 biases the valve member 208 toward valveseating position.

It should be noted that in all forms of the invention herein describedthe fuel inlet control system embodies a second class lever viz. a leverfulcrumed at one end, engaged by a spring at a region spaced from thefulcrum.

It is apparent that, within the scope of the invention, modificationsand different arrangements may be made other than as herein disclosed,and the present disclosure is illustrative merely, the inventioncomprehending all variations thereof.

I claim:

1. In combination, charge forming apparatus including a body formed witha mixing passage, a fuel chamber formed in the body, a throttle valve inthe mixing passage, a flexible diaphragm having one side forming a Wallof the fuel chamber and its other side having an unsupported centerportion, said mixing passage being formed with a main Venturi, asupplemental Venturi of reduced size in the main Venturi and having itsaxis parallel to i and offset from the axis of the main Venturi towardthe diaphragm, an orifice opening into the supplemental Venturi, a fuelinlet insaid body, a valve for said fuel inlet, a lever fulcrumed in thefuel chamber engageable with the inlet valve, said lever being engagedwith and actuated by the diaphragm for transmitting movement of thediaphragm through the lever to position the inlet valve for controllingfuel flow into the fuel chamber, a portion of said lever extendingsubstantially parallel to said diaphragm, pivot means for said lever,said pivot means being offset from the central axis of said diaphragm,means biasing the inlet valve toward closed position, said fuel chamberbeing unvented whereby the diaphragm is actuated solely by differentialpressure in the mixing passage, and passage means for conveying fuelfrom the fuel chamber to the orifice.

2. In combination, charge forming apparatus as in claim 1 and including:

(a) spring means acting on the parallel portion of said said lever.

3.1m combination, charge forming apparatus as in claim 1 and including:

(a) spring means acting on the parallel portion of said lever andpositioned between said pivot means and the central axis of saiddiaphragm.

4. In combination, charge forming apparatus as in claim 1 and wherein:

(a) said lever is of the second order of levers.

5. In combination, charge forming apparatus as in claim 1 and wherein:

(a) said lever is L-shaped.

6. In combination, charge forming apparatus including a body formed witha mixing passage, a fuel chamber formed in the body, a throttle valve inthe mixing passage, a flexible diaphragm having one side forming a wallof the fuel chamber and its other side having an unsupported centerportion, said mixing passage being formed with a main Venturi, asupplemental Venturi of reduced size contained within the main Venturiand having its axis parallel with and offset from the axis of the mainVenturi toward the diaphragm, a main orifice opening into thesupplemental Venturi, a secondary orifice opening into the mixingpassage, a fuel inlet in said body, a valve for said fuel inlet, afulcrum pin extending into the fuel chamber, a lever in the fuel chamberfulcrumed upon the pin and engageable with the inlet valve, said leverbeing engaged by the diaphragm for transmitting movement of thediaphragm through the lever to position the inlet valve for controllingfuel flow into the fuel chamber, a portion of said lever extendingsubstantially parallel to said diaphragm, said fulcrum pin being offsetfrom the central axis of said diaphragm, a spring biasing the inletvalve toward closed position, said fuel chamber being unvented wherebythe diaphragm is actuated solely by differential pressure in the mixingpassage, passage means for conveying fuel from the fuel chamber to themain and secondary orifices, and means to prevent back bleeding of airthrough the main orifice when the secondary orifice is delivering fuelinto the mixing passage.

References Cited by the Examiner UNITED STATES PATENTS 2,141,365 12/1938Schuttler. 2,252,958 8/1941 Bicknell 261-34 2,638,330 5/1953 Morgenroth26l64 X 2,796,838 6/1957 Phillips. 2,724,584 11/1955 Armstrong 261692,733,902 2/1956 Phillips 261-41 2,774,582 12/1956 Bracke 26 1412,796,838 6/1917 Phillips. 2,823,905 2/1958 Brown 26l37 2,841,372 7/1958Phillips 261-41 2,898,095 8/1958 An 26l23 2,985,159 5/1961 Moseley 26l72X 3,072,390 1/1963 Phillips 26135 3,118,009 1/ 1964 Phillips 261-35HARRY B. THORNTON, Primary Examiner.

RONALD R. WEAVER, Examiner.

1. IN COMBINATION, CHARGE FORMING APPARATUS INCLUDING A BODY FORMED WITHA MIXING PASSAGE, A FUEL CHAMBER FORMED IN THE BODY, A THROTTLE VALVE INTHE MIXING PASSAGE, FLEXIBLE DIAPHRAGM HAVING ONE SIDE FORMING A WALL OFTHE FUEL CHAMBER AND ITS OTHER SIDE HAVING AN UNSUPPORTED CENTERPORTION, SAID MIXING PASSAGE BEING FORMED WITH A MAIN VENTURI, ASUPPLEMENT VENTURI OF REDUCED SIZE IN THE MAIN VENTURI AND HAVING ITSAXIS PARALLEL TO AND OFFSET FROM THE AXIS OF THE MAIN VENTURI TOWARD THEDIAPHRAGM, AN ORIFICE OPENING INTO THE SUPPLEMENTAL VENTURI, A FUELINLET IN SAID BODY, A VALVE FOR SAID FUEL INLET, A LEVER FULCRUMED INTHE FUEL CHAMBER ENGAGEABLE WITH THE INLET VALVE, SAID LEVER BEINGENGAGED WITH AND ACTUATED BY THE DIAPHRAGM FOR TRANSMITTING MOVEMENT OFTHE DIAPHRAGM THROUGH THE LEVER TO POSITION THE INLET VALVE FORCONTROLLING FUEL FLOW INTO THE FUEL CHAMBER, A PORTION OF SAID LEVEREXTENDING SUBSTANTIALLY PARALLEL TO SAID DIAPHRAGM, PIVOT MEANS FOR SAIDLEVER, SAID PIVOT MEANS BEING OFFSET FROM THE CENTRAL AXIS OF SAIDDIAPHRAGM MEANS BIASING THE INLET VALVE TOWARD CLOSED POSITION, SAIDFUEL CHAMBER BEING UNVENTED WHEREBY THE DIAPHRAGM IS ACTUATED SOLELY BYDIFFERENTIAL PRESSURE IN THE MIXING PASSAGE, AND PASSAGE MEANS FORCONVEYING FUEL FROM THE FUEL CHAMBER TO THE ORIFICE.